A "26-L" air brake system is an equipment package which has been designed to meet present day train handling requirements. This system uses air, under pressure, for the braking of locomotives and trailing freight or passenger vehicles. This system has been designed and developed by the Westinghouse Airbrake Company (WABCO), the assignees of the present invention.
A "26-L" system includes air brake control valves on the cars/locomotives which are the primary controlling devices in this equipment arrangement. These valves provide the manual means for initiating air brake applications and releases. FIG. 1 shows a 26 control valve currently in use. This control valve has a service portion 13 which includes components thereon that allow for proper development of brake cylinder pressure proportional to the reduction or increase in brake pipe pressure, thus permitting stable operation of the automatic brake together with proper development of brake cylinder pressure. A release cap 14 is mounted on the service valve portion 13 and is used to manipulate the valve characteristics so that the valve can perform a "graduated" or "direct" release operation. A graduated release position is to be used for passenger type locomotive service in trains and a direct release position is to be used for freight type locomotive service.
These presently used release caps 14 necessitate their total removal thereof from the body of the valve in order to change the valve from a direct to a graduated or a graduated to a direct position. This requires excessive time and necessitates tool requirements. This time is considered a major hindrance when converting a set-up train from a direct brake cylinder system to a graduated brake cylinder system.